Hydraulically operated wheel feeding mechanism



' March 9, 1937.

w; H. WOOD 2,073,574 HYDRAULICALLY OPERATED WHEEL FEEDING MECHANISM Filed July 16, 1955 2 Sheets-Sheet 2 s4 WI 555 75 63 WA L LA CE H WOOD Patented Mar. 9, 1937 PATENT OFFICE HYDRAULICALLY OPERATED WHEEL FEED- ING MECHANISM Wallace H. Wood, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application July 16, 1935, Serial No. 31,633

13 Claims.

This invention relates to grinding machines, and more particularly to a hydraulically operated wheel feeding mechanism.

Heretofore, various feeding mechanisms have been devised operated either mechanically or hydraulically. In most cases, these mechanisms have been arranged for either a plunge-cut feed, that is, where the grinding wheel is of suificient width to grind the entire length of the work piece while it is fed directly and continuously into" the work axis, or have comprised a mechanism which is operated in timed relation with thework table reciprocation to cause an infeeding movement of I the grinding wheel when the work table is reversed-at the end of itsreciprocatorystroke.

In certain types of grinding, it is desirable to provide a hydraulically operated wheel feeding mechanism which is so arranged that the mechanism may be hydraulically actuated intermittently at the end of the reciprocatory stroke of the work table'or may be fed directlyby the so-called plunge-cut infeeding of the wheel when there is no relative traverse between the wheel and work. This mechanism is preferably so arranged that the feed may be readily changed from a plunge-cut to a traverse grinding feed.

It is one object of this invention to provide a hydraulically operated wheel feeding mechanism which may beoperated either for a plunge-cut grinding operation or for an intermittent infeed at the end of .the reciprocatory strokeof the table. It is a further object of, this invention to provide a hydraulically actuated-picker wheel feeding mechanismin' which the picker is reciprocated continuously'by' a fluid pressure motor so that a plunge-cut infeed may be obtained. It is a further object to provide apicker feed mechanism in which the pickermay be oscillated by means of a hydraulic motor a'tjthe" end of the table stroke to cause an intermittent infeed of the wheel in a traverse grindin'gi'operation. It is a still further object ofthis invention to provide a picker actuated wheel feed in which the picker is reciprocated by afluidpre'ssure motor in which the-motor-mayfbe operated continuously to obtain-a plunge-cutiinfeed or may be operated intermittently at the eji'idsfiof the table stroke to obtain an wheelfeedzfor traverse grinding. v

Other objects be apparent from the foregoing disclosure. One embodiment ofthis invention has been illustrated in the accompanying drawings, in which like reference numerals indicate like parts.

Fig. 1 is a fragmentary front elevation of the improved grinding wheel feed mechanism having parts broken away and shownin section to more clearly show the construction;

Fig. 2 isa similar fragmentary front elevationof the feeding mechanism having parts broken away and shown in section, as well as showing diagrammatically the fluid pressure piping system;

'Fig. 3 is a fragmentary cross-sectional view, on a reduced scale, showing the arrangement of the wheel slide, work table, table traverse and wheel feeding mechanisms;

Fig. 4 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line 4-4 of Fig. 1;

' Fig. 5 is a fragmentary vertical section, on an enlarged scale, taken approximately on the line 5-5 of Fig. 4; and

Fig. 6 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line 6-6 of Fig. 1, showing the spring pressed ball for locating the reversing valve in. one of two positions for obtaining either a plunge-cut or an intermittent feed.

The embodiment of this invention illustrated in the drawings comprises a base It which supports a transversely movable wheel slide II on slideway l2. The wheel slide Ii supports a rotatable grinding wheel II which may be driven by any suitable source of power. For the sake of illustration, an electric motor it is mountedon the top of the wheel slide I l and is connected by a motor pulley IS, a belt it, with a pulley il on the end of a wheel spindle I8.

a The base It alsosupports a longitudinally movable table 25 which is supported on theusual flat way 26 and v-way 21. The table is providedwith .a rotatable work supporting means, such as a ed on the inner end of a rotatable shaft 39. The outer end of the shaft 39 is provided with a gear 40 which meshes with a small gear 4! carried by a shaft 42 which also supports a picker feed wheel 43. The picker wheel is of standard construction and similar to that shown in the prior 17. S. patries agear I! which meshes with agear l'l mounting wheel l3. A fixed abutment 41. is carried by v the manually operable handle 44 which is arranged in the path of the picker 46 to limit the infeeding movement of the grinding wheel. A micrometer adjusting mechanism 48 is provided to reset the abutment 41 relative to the wheel 43 so that it may be adjusted to vary the extent of infeeding in case of wheel wear or in setting up the mechanism for a given grinding operation.

The table 25 may be reciprocated by any suitable reversing mechanism, either manually or by power. A manually operable table traverse mechanism has been illustrated, including a rack bar 58 depending from the table 25 which meshes with a gear 5| mounted on the inner end of a rotatable shaft 52. The shaft 52 is journalled in suitable bearings (not, shown) in the base I8 and is provided at its outer end with a manually operable traverse wheel 53.

The table 25 may also be reciprocated by a mechanical or hydraulic mechanism, the details of which have not-been fully illustrated and described in the present case since this mechanism is not considered to be a part of the present invention. For a detailed description of such a mechanism, reference may be had to my copending U. S. patent application Serial No. 741,119 filed August 23, 1934. This mechanism comprises a reversinglever 68 which is pivotally mounted on a stud 6| on the front of the machine base l8. The reversing lever 68 is arranged to be shifted by a pair of adjustable dogs 62 and 54 which engage a pin 55 on the lever 68 and shift the same so as to actuate the reverse lever and thereby change the direction of movement of the table.

To attain the main object of this invention, a suitable hydraulic mechanism is provided which permits either an infeeding movement of the rinding wheel at each reversal of the table or a continuous plunge-cut or straight-in feed of the wheel when no reciprocation of the table is'utilized. This mechanism may comprise a fluid pres sure cylinder 63 having a piston 64 slidably mounted therein. The piston 64 is connected by a piston rod 65 and a connecting link 66 with a vertically movable slide 61 which is mounted in a slideway 68 on the front of the machine base. The picker 46 is pivotally mounted on a stud on the slide 61. It will be readily apparent that when the piston 64 is reciprocated, the picker 46 will be caused to move up and down relative to the picker wheel and will pick successive teeth on the wheel 43, thereby causing the grinding wheel 13 to be fed into the work 23. This mechanism functions the same regardless of whether a continuous plunge-cut feed or an intermittent feed during table reversal is used. An adjustable stop 63 on the link 66 engages the lower surface 18 of the slideway 68 and serves to limit the upward movement of the picker 46. The stop 63 has a reduced threaded portion 1| which passes through an elongated slot 12 in link 66 and maybe clamped in adjusted position thereon by means of a nut 13. By adjusting the position of stop, the stroke of the picker 46 may be adjusted so that one or more teeth on the picker wheel 43 will be picked up at each actuation of the picker 46.

The fluid pressure system comprises a reservoir 15 which is preferably located in the base J8 of the machine. Fluid is pumped from the reservoir 15 through a pipe 16 by means of a pump 11 and is forced through a pipe 18 into a control valve 19. The control valve is of a piston type including a valve piston 88, the upper end of which is formed with an arrow point surface 8| arranged in the path of an adjustably positioned arrow point 82 on the reverse lever 68.

The piston 88 is held normally in an upward position against an adjustable stop screw 83 by means of a spring 84. The stop screw 83 is ad- J'ustably mounted in a lug 85 projecting from a frame 86. In the upper position of the piston 88,

' fluid under pressure passing from the pump 11 passes through pipe 18, into a valve chamber 86 in control valve 13 and through a passage 81 into cylinder chamber 88 to cause the piston 64 to move downwardly. The downward movement of the piston serves to cause a downward movement of the picker 46, which turns the picker wheel 43 in a'counterclockwise direction to cause an infeeding movement of the grinding wheel. When the piston 88 is in its normally upper position, fluid may exhaust from cylinder chamber 83, through a. passage 38 into a valve chamber 3| and exhaust through a pipe 32 into reservoir 15.

Assuming the table to be traveling in the di rection of the arrow (Fig. 2), the piston 88 remains in a normally upward positiorrwith the plate 35 in engagement with stop screw 83 until the reverse dog 54 engages the reverse lever 68 and swings it into position 68a to reverse the direction of movement of table 25. During the swinging movement of lever 68 from full line position to broken line position 68a, the arrow point 82 rides over the arrow point 8| and causes a downward movement of control valve piston 88 against the tension of the spring 84 so that valve piston 88 instantaneously assumes a. position such as that shown in Fig. 2. In this position of piston 88, both the passages 81 and 38 open into 'valve chamber 86. In this position, fluid under pressure from pipe 18 may pass through both ports 38 and 81 into cylinder chambers 83 and 88 respectively. Due to the differential in the effective areas of the upper and lower surfaces of piston 64, the fluid pressure entering the valve chamber 86 will cause the piston 64 to move upwardly, during which time the fluid within the cylinder chamber 88 will be forced through passage 81 due to the differential of pressures on the upper and lower surfaces of the piston 64 and supplements the fluid under pressure entering chamber 86 through pipe line 18. In this position of the parts, the piston 64 moves upwardly, carrying the picker 46 through an idle upward stroke so that it is ready to engage the additional teeth on the picker wheel 43 to cause a further infeeding of the grinding wheel when the control valve piston 88 is moved upwardly under the influence of spring 84. The speed of upward movement of the piston 64 is governed by the differential in piston areas and also by the extent of the downward movement of valve piston 88 caused by the adjustable arrow point 82. By varying the position of arrow point 82 on the lever 68, the extent of opening of passage 38 into valve chamber 86 may be varied. It will be noted that the piston rod 65 is of a substantial diameter relative to the diameter of the piston 64 so that the eifecover the high point of arrow surface 8|, the

) "released tension of spring 84 causes the valve piston 80 to move upwardly. This movement cuts off the passage 90 from the valve chamber 86. Fluid under pressure then passes through passage 81 into cylinder chamber 88 -and causes adownward movement of piston 64 and an infeeding movement of picker 46 and feed wheel 43. During the downward movement of piston 64, fluid exhausts from the cylinder chamber 89, through the passage 90, the valve chamber 9|, the pipe 82, into reservoir 15.

It will be readily apparent from the foregoing disclosure that each time the table reverse lever 60 is moved from position 60 into position 60a,

or from position 60a into position 60, the valve piston 80 is moved downwardly to cause .an upward or idle stroke of the picker 46 relative tothe picker feed wheel 43, and when the piston 80 is returned to its normal'upward position, the fluid under pressure is passed into cylinder chamber 88 to cause a downward movement of piston 64 I and a feeding movement between picker 46 and picker wheel 43.

Plunge-cut feed In certain types of grinding, where the portion of the work to be ground is equal to or less than the width of the operative face of the grinding wheel, no traversing movement of the table is required. In such an operation, it is desirable to feed the grinding wheel directly and continuously into the work by what is known as a straight-inv or plunge-cut feed. To attain one of the objects of this invention, a suitable means is provided which serves to permit either a feed at reversal or a plunge-cut infeeding movement of the grinding wheel. It is desirable to utilize the same piston 64, cylinder 63 and control valve 18 and to supplement these parts with an additional mechanism so that the control valve may be operated of a spring I which surrounds a plunger IOI and is interposed'between a head I02 on plunger IOI and a projection I03 of the frame 14. The

tension of the spring I00 is greater than the ten-- sion of the spring 84 so that when the spring I 00 is in an operating position with head I02 in engagement withplate 95, the greater tension of spring I00 serves to hold the control valve piston 80 normally in a downward position. Whenit is desired to operate the mechanism to obtain an infeeding movement of the grinding wheel for a traverse grinding operation, that is, at the end I of the work table stroke during the period of reversal, the spring I00 must be held ineffective so that thecontrol valve piston 80, during such operation, is held in a normally upward position, as previously described. To accomplish this result, a handle I04 is provided on the upper end of the plunger WI and a lock pin I05 is arranged to engage the upper end surface of projection I03 of the casing when plunger IN is raised vertically and handle I04 rotated so that lock pin I05 slides out of engagement with a vertical elongated slot I06. This movement raises the head I02 out of contact with the plate 95. When it is desired to utilize the feeding mechanism for a plunge-out feeding operation, the handle I04 is turned so that pin I05 slides into the elongated slot I06 and releases the tension .of spring I00 to force the head I02 downwardly into operating engagement with the plate 95 to move valve piston 80 downwardly and hold it in a normally downward position during the plunge-cut feeding operation. In this position of the parts, fluid under pressure from pipe line 18 passes into valve chamber 86 and due to the fact that both passages 81 and 80 are open into chamber 86, serves to cause the piston 64 to move upwardly into the position illustrated in Fig. 2.

In order that the piston 64 may be reciprocated, a pilot valve I01 is provided which has a pin I08 arranged in the path of a pair of reversing dogs I09 and H0 which are adjustably mounted on a pin III supported by an arm'I I2. The arm H2 is rigidly fixed to the link 66. In the position of the parts illustrated in Fig. 2, the dog I09 has engaged the pin I08 and further upward movement of the piston 64 serves to move the pilot valve I01 upwardly so that pilot valve piston II3 uncovers from pipe '18 to pass through valve chamber 86, passage 81, cylinder chamber 88, passage II4, into pilot valve chamber H5, and pass through a passage II6 into a control valve chamber II1 to cause the valve piston 80 tov move upwardly against the tension of-spring' I00. When the control valve piston 80 reaches its uppermost position, it closes the passage 90 so as t6 cut 01! fluid pressure from the cylinder chamber 86'.- In this position of the parts, fluid under pressure from pipe 18 passes through the control valve chamber 86, the passage 81, into the cylinder-chamber 88 and causes a downward mdvementcf the piston 64 which in turn causes a'dow'nward infeeding movement of picker 46 to turn the picker wheel a passage H4 and allows fluid under pressure 64, the dog IIO engages the pin I08 and moves the pilot valve I01 downwardly a suflicient distance so that the piston I I 3 closes the passage I I4 and cuts oif pressure from the passage II6. A

pilot valve piston I20 moves downwardly through" a sufflcient distance to open an exhaust pipe I-2I which allows fluid to exhaust from the control valve chamber II1 through the passage I I6, into the pilot valve chamber H5 and out through the exhaust pipe I2I and into .the reservoir 15. Relieving the pressure from the chamber II1 releases the tension of the spring I00 and allows the control valve piston 80 tomove downwardly into the position illustrated in Fig. 2. When the piston 80 assumes the downward position, fluid may again pass through the pipe 18, the valve chamber 86; and the passages 81 and 90 being openserves to cause an upward movement of piston 64 and an idle .movement of the picker 46 relative to the picker feed wheel 43. It will be readily apparent from the foregoing disclosure that the pilot valve I01 togethenwith the dogs I09 and H0 serve to cause an intermittent continuous infeeding movement of the grinding wheel when work is to "be ground by the plunge-cut method.

When it is desired to stop the continuous infeed, the pilot valve I01 must be retained in a downward position, such as that shown in Fig. 2.

This is preferablyaccomplished by.means of a" handle I24 mounted on the upper end of the pilot v'alve I01 which serves to rotate the valve I 01 and locate it in one of two positions by means of a spring-pressed ball I22 (Fig. 6) which engages V-notches I23 in the valve stem I0I. When the handle I24 is in the full line position indicated in Fig. 4, the pin I08 is in the position indicated, in the path of both dogs I08 and H0. When it is desired to stop the continuous or plunge-cut feed, the handle I24 is moved into position I24a which serves to shift the pin I08 into position I08a. The lower dog I09 is slabbed off on one side to provide a surface in the line of a chord I33 so that when the dogs are moved downwardly, the dog IIO strikes the pin I08 and moves the pilot valve I01 into itsdownward position. On the next upstroke of the pistonj64, the dogs I09 and H0 are moved upwardly but due to the slabbed-ofi portion of the dog I09, the dog I09 will pass by and not engage the pin I08. This allows the pilot valve I 01 to remain in its lower position. The operator may then turn the handle I 04 into position I04a so as to release the tension of the spring I 00 and allows the control valve piston to return to its normally upward position under the influence of the spring 84 so that an infeeding movement at reversal may be obtained.

The speed of the upward movement of the picker 46 may be varied to obtain either a fast or a slow return or idle movement of the picker. By adjusting the position of arrow point 82 relative to the lever 60, the extent of the upward movement of control valve piston 80 may be varied. Variation in the extreme downward position of piston 80 serves to vary the opening of passage relative to control valve chamber 86. .This opening from the valve chamber 86 into passage 90 varies the amount of fluid under pressure that may be admitted to cylinder chamber 89 and consequently varies the speed of upward movement of the piston 64. v The speed of the downward or infeeding movement of the picker 46 may be varied by means of a valve I25 in the exhaust pipe 82 which serves to throttle the exhaust of fluid from the cylinder chamber 89. When the control valve piston 80 is in its uppermost position with the plate in engagement with the screw 83 and the piston 64 moves downwardly, fluid exhausts from the cylinder chamber 89, through the passage 90, the control valve chamber 9|, and out through the pipe 92 and the valve I25 into the reservoir 15. It will be readily apparent from the foregoing disclosure that adjustment of the valve I25 serves to control the speed of the downward movement of the picker 46 and thereby varies the speed of the ini'eeding movement.

An exhaust passage I26 is provided to permit drainage of any fluid in a valve chamber I2'I which leaks by the valve piston I20. This fluid from chamber I21 flows into a reservoir I28 formed within the frame I4. Fluid within reservoir I28 overflows through a pipe I29 and returns to reservoir I5.

The operation of this machine is readily apparent from the foregoing disclosure. Assuming the dogs 62 and 54 to be adjusted to the required position and the arrow point 82 and stop screw 83 have been adjusted, and the stop 69 has been adjusted to give the desired movement of the picker, the grinding operation may be started and as the table 25 is reciprocated, the reverse lever 60 is shifted from position 60 to 60a or vice versa, serving through arrow points 82 and 8I to cause a downward movement of the control valve piston 80 to cause an idle upward movement of the picker 46. The return or upward movement of the piston 80 under the influence of spring 84 serves to cause a downward infeeding movement of picker 46. This infeeding of the grinding wheel will continue at each reversal of the table.

When it is desired to cause a straight-in or plunge-cut feed of the wheel, the operator moves the handle I04 downwardly to lock the spring I00 under operating tension to maintain valve piston 80 in a normally downward position. The handle I24 is then rotated from position I24a into full line position I24 (Fig. 4) which serves to move the pin I08 from position I08a into po-' sition I 08 to render the pilot valve efiective to admit fluid to the control valve so that it functions to continuously reciprocate the piston 54 and cause a continuous reciprocation of the picker 46 and thereby produce a continuous infeeding movement of the grinding wheel.

In the operation of the machine as illustrated in Fig. 2 of the drawings, the infeed by means of the picker continues until the picker rides upon the shield I29. The operator may then manually turn the feed wheel to bring the abut- .ment 41 into contact with the end of picker 46 to positively limit the infeeding movement to size the work.

If it is desired to feed the wheel by means of the picker 46 to size the work, it is necessary to provide a movable stop I 30 which is pivotally mounted on a bracket I3I fixed to the base of the machine which when in an operative position is engaged by abutment 41 on the feed wheel to positively limit the infeeding movement of the grinding Wheel before the picker 46 rides upon the shield I 29. The stop I30 is pivotally connected to the bracket so that it may be readily swung to an inoperative position I30a.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A grinding machine comprising a longitudinally movable work supporting table, a transversely movable grinding wheel slide, means including a reversing lever to reciprocate said table, a feeding mechanism operatively connected to cause a transverse feeding movement of said slide, a fluid pressure piston and cylinder operatively connected to actuate said feeding mechanism, a control valve for controlling the admission of fluid under pressure to said cylinder, and means including a pilot valve actuated in timed relation with said piston to control-the admission of fluid to actuate said control valve so as to cause a continuous reciprocation of said piston and to continuously actuate said feed mechanism so as to produce a straight-in or plunge-cut feeding movement of the grinding wheel slide.

2. A grinding machine comprising a longitudinally movable work supporting table, a transversely movable grinding wheel slide, means including a reversing lever to reciprocate said table, a feeding mechanism operatively connected to cause a transverse feeding movement of said slide, a fluid pressure piston and cylinder operatively connected to actuate said feeding mechanism, a control valve for controlling the admission of fluid under pressure to said cylinder, and means including a pilot valve actuated by movement of said piston to control the admission of fluid to actuate said control valve so as to cause a continuous reciprocation of said piston and to continuously actuate said feed mechanism so as to produce a straight-in or plunge-cut feeding movement of the grinding wheel slide.

3. A grinding machine comprising a longitudinally movable wo rk supporting table, a trans- ,versely movable grinding wheel slide, means including a reversing lever to reciprocate said table, a feeding mechanism operatively connected to cause a transverse feeding movement of said slide, a fluid pressure piston and cylinder operatively connected to actuate said feeding mechanism, a control valve for controlling the admission of fluid under pressure to said cylinder,

4. A grinding-machine comprising a longitudinally movable work supporting table, a transversely movable grinding wheel slide, means including a reversing-lever to reciprocate said table, a feeding mechanism operatively connected to move said slide transversely, a fluid pressure system including a piston and cylinder operatively connected to actuate said feeding mechanism, a

control valve ,operatively connected to control the admission of fluid to said cylinder, means actuated by said reverse lever to actuate said control valve and cause said piston to reciprocate once at each actuation of the reverse lever to cause an infeeding movement of the grinding wheel at the end of the work table stroke, means to render said control valve inoperative with relation to said reverse lever and a pilot valve so as to cause a continuous reciprocation of said piston to produce a straight-in or plungecut feeding movement of the grinding wheel slide. V

5. A grinding machine comprising a longitudithe work table stroke, means to render said control valve inoperative with relationto said reverse lever, adjustable dogs actuated by said piston, and a pilot valve actuated by said dogs to control the admission of fluid to said' control valve so as to cause a continuous reciprocation of said piston to produce a straight-in or plunge-cut feeding movement of the grinding wheel slide.

7. A grinding machine comprising a longitudinally movable work supporting table, a transversely movable grinding wheel slide,'means including a reversing lever to reciprocate said table,

a feeding mechanism operatively connected tomove said slide transversely, a fluid pressure 885-,- tem'including a piston and cylinder operatively connected to actuate said feed mechanism, a

control valve operatively connected to control the admission of fluid to said cylinder, means including a pilot valve to control the admission ofv fluid to said control valve so as to cause a, continuous valve to control admission of fluid to said control nally movable work supporting table, a transversely movable grinding wheel slide, means including a reversing lever to reciprocate said table, a feeding mechanism operatively connected to move said slide transversely, a fluid pressure system including a piston and cylinder operatively connected to actuate said feeding mechanism, acontrol valve operatively connected to control the admission of fluid to said cylinder, means actuated by said reverse lever to actuate said control valve and cause said piston to reciprocate once at each actuation ofthe reverse lever to cause an infeeding movement of the grinding wheel at the end of the work table stroke, means to render said control valve inoperative with relation to said reverse lever, and a pilot valve actuated by said piston to control admission of fluid to said control valve so as to cause a continuous reciprocation of said piston to produce a straightin or plunger-cut feeding movement of the grinding wheel slide.

6. A grinding machine comprising a longitudinally movable work supporting table, a transversely movable grinding wheel slide, means including a reversing lever to reciprocate said table, a feeding mechanism operatively connected to move said slide transversely, a fluid pressure system including a piston and cylinder operatively connected to actuate said feeding mechanism, a control valve dperatively connected to control the admission of fluid to said cylinder, means actuated by said reverse lever to actuate said control valve and cause said piston to reciprocate once at each actuation of the reverse lever to cause an infeeding movement of the grinding wheel at the end of nally movable work supporting table, a transversely movable grinding wheel slide, means including a reversing lever to reciprocate said table, a feeding mechanism operatively connected to move said slide transversely, a fluid pressure system including a piston and cylinder operatively connected to actuate said feeding mechanism, a control valve operatively connected to control the admission of fluid to said cylinder,

adjustable dogs actuated. in timed relation with said piston movement,- a pilot valve. actuated by said dogs to'control theadmission of fluid tosaid control valve so as to-cause a continuous reciprocation of said piston-to produce a straight-in or plunge-cut feeding movement of the grinding wheel slide, means to render said pilot valve inoperative with relation to said dogs, and means actuated bysaid reversing lever to operate said control valve and cause said piston to produce aninfeeding movement of the grinding wheel slide when the reversing lever is shifted at'the end' of the work table stroke for a traverse grinding feed. e p

9. A grinding machine comprising a rotatable grinding wheel, a transversely movable wheel 1 slide to support said wheel, a longitudinally movable table, means including a reversing lever to reciprocate said table, means including a movable picker and rotatable feed wheel actuated thereby to cause a transverse feeding movement of the grinding wheel, a fluid pressure mechanism operatively connectedto actuate said picker, a control valve for controlling the admission of fluid tosaid mechanism, means actuated by the reverse lever to actuate said control valve .to

10. A grinding machine comprising a rotatable grinding wheel, a transversely movable wheel slide to support said wheel, a longitudinally movable table, means including a reversing lever to reciprocate said table, means including a movable picker and rotatable feed wheel actuated thereby to cause a transverse feeding movement of the grinding wheel, a fluid pressure mechanism including a piston and cylinder which are operatively connected to actuate said picker, 2. control valve which is arranged to control the admission of fluid to said cylinder, means actuated by said reverse lever to actuate said con-l trol valve to cause an infeeding movement at each end of the table stroke, a second control valve actuated by and in timed relation with the movement of said piston continuously to reciprocate said'piston and picker, means to render said control valve inoperative by said reverse lever during the plunge-cut feedingmovement, and means to render said second valve inoperative during the intermittent feeding movement.

11. A feeding mechanism for a cylindrical grinding machine comprising a movable picker, a feed wheel actuated thereby, a stop abutment on said wheel, a fixed stop in the path of said abutment to positively limit the infeeding movement, a reciprocable slide arranged to support piston and cylinder which is actuated by dogs carried by said piston to change the direction of movement of said picker.

12. A feeding mechanism for a cylindrical grinding machine comprising a movable picker, a feed wheel actuated thereby, a reciprocable slide arranged to support said picker, fluid pressure means including a piston and cylinder operatively connected to reciprocate said slide, an adjustable stop associated with said piston to limit the movement of said picker in one direction so asto vary the extent of movement of the picker and thereby vary the extent of feeding movement of the grinding wheel, means including a valve associated with said piston and cylinder, and adjustable dogs carried by said piston to actuate said valve to change the direction of movement of said picker.

13. A wheel feed mechanism for a grinding machine comprising a rotatable grinding wheel, a transversely movable slide to support said wheel, a nut and screw mechanism to cause a feeding movement of said slide, means including manually operable feed wheel to rotate said screw 7 to cause a forward or rearward feeding movement of the grinding wheel, a movable picker arranged to turn the feed wheel, means including a fluid pressure piston and cylinder which are operatively connected to actuate said picker,

a valve arranged to admit fluid under pressure to opposite ends of said cylinder to cause said picker to move in opposite directions, adjustable dogs movable in timed relation with said picker which are arranged to shift the valve to cause a continuous reciprocation of the picker so as to produce a continuous direct infeed of the grinding wheel.

WALLACE H. WOOD. 

